Indications for blood purification in critical care

Blood purification in critical care can perform 2 main functions: as an artificial support for failing organs (such as artificial kidney or liver support) and as a remover of causative humoral mediators of critical illness (such as severe sepsis and acute respiratory distress syndrome). As an artificial kidney, continuous blood purification (such as continuous hemofiltration and continuous hemodiafiltration, CHDF) is widely applied in intensive care units. The intensity of renal replacement therapy, however, has been reported to have no impact upon the efficacy of the blood purification in terms of clinical outcome. Concerning blood purification and the removal of causative humoral mediators of critical illness, CHDF using a hemofilter made from polymethylmethacrylate membrane is reported to be very effective in the treatment of severe sepsis and septic shock, even in septic patients without renal dysfunction. Thus, in Japan, CHDF with a polymethylmethacrylate membrane is now widely applied for non-renal indications, not only for patients with sepsis but also patients with cytokine-induced critical illness (such as acute respiratory distress syndrome and severe acute pancreatitis), even when those patients do not present with renal dysfunction. However, our understanding of the pathophysiology of sepsis has changed since the concept of pattern recognition receptors and pathogen-associated molecular patterns was introduced. According to this, CHDF with a cytokine-adsorbing polymethylmethacrylate membrane hemofilter is preferable and more effective than direct hemoperfusion with an endotoxin-adsorbing polymyxin-B immobilized column in the treatment of sepsis and septic shock. Blood purification in critical care is gaining popularity, and is widely for both renal and non-renal indications.